THE MUSCLES. 29 



d. How much power must be exerted to lift a weight 

 of twenty pounds resting on the hand, when the forearm 

 is in a horizontal position ? 



2. The triceps muscle of the back of the arm does part 

 of the work of the arm. It is attached just back 

 of the elbow-joint. 



a. Where is the weight? the fulcrum? 



b. Which kind of lever is this? 



c. How much power must be exerted by the triceps 

 muscle to make the hand push twenty pounds? 



I. The Lever in the Foot and Leg. 



When standing on the toes, the bones of the foot act as 

 a lever. The power is in the muscles of the calf of the leg. 



a. Where is the weight? How much is it? 



b. How long are the power and the weight arms ? 



c. Which kind of lever is this ? 



d. How much power is required for a person weighing 

 125 pounds to stand on his toes? How much is required 

 for you to stand on your toes ? 



J. A Model of an Arm. 

 NOTE. This is adapted from WoodhulPs IIome-Made Apparatus. 



Apparatus. One piece of wood 4 in. x 3 in. x 1 in. 

 " " 9 in. x 1 in. x 1 in. 



" " 4 in. x 1 in. x 1 in. 



Three rubber bands. Six hooks. Four small strips of tin about an 

 inch long. 



The general arrangement of the muscles in the arm may 

 be obtained from a model of wood with muscles of rubber 



